Modulation of electronic spin state and construction of dual-atomic tandem reaction for enhanced pH-universal oxygen reduction

Combining both advances of electronic spin state modulation and tandem reaction mechanism, an atomic-level dual iron-copper catalyst is designed for enhanced oxygen reduction capability. Herein, the intense interaction between the iron-copper site and its coordination environment can not only controls the flow of external charge at the atomic level, but regulates the internal 3d electron configuration. These modulations can optimize the orbital interaction and pair hardness (ηDA) between the acceptor and the donor, and achieves a fast tandem reaction kinetics, thereby surmounting the limitation of Scaling Relation. The as-prepared bimetal catalyst validates a high ORR activity and stability, which even exceed those of the benchmark Pt/C in pH-universal electrolytes. Meanwhile, Fe,Cu/N-C driven Zn-air batteries in alkaline and neutral electrolytes show prominent performance with peak power densities of 173.7 mW cm−2 and 86.5 mW cm−2. This work provides a useful design principle for developing or optimizing other efficient ORR catalysts.